With increasing acceptance that petroleum hydrocarbon supplies are decreasing and their costs are ultimately increasing, interest has increased for developing and improving industrial microbial systems for production of chemicals and fuels. Such industrial microbial systems could completely or partially replace the use of petroleum hydrocarbons for production of certain chemicals.
Numerous chemicals are produced through such means, ranging from antibiotic and anti-malarial pharmaceutical products to fine chemicals to fuels such as ethanol. Commercial objectives for microbial fermentation include the increase of titer, production rate, and yield of a target chemical product. When the overall specific productivity in a fermentation event is elevated, this may positively affect yield in addition to production rate and other economic factors, such as capital costs.
One candidate chemical for such production is 3-hydroxypropionic acid (“3-HP”, CAS No. 503-66-2), which may be converted to a number of basic building blocks for polymers used in a wide range of industrial and consumer products. Unfortunately, previous efforts to microbially synthesize 3-HP to achieve commercially viable titers have revealed that the microbes being used were inhibited by concentrations of 3-HP far below a determined commercially viable titer.
In spite of strong interest to improve microbial fermentation economics by improving yield and/or productivity for certain chemical products, there remains a need to increase net conversion in a fermentative microorganism cell to desired target chemical products employing commercially viable fermentation methods. More particularly, among problems remaining to be solved are how to improve specific productivity and volumetric productivity, such as to economically important levels, in modified microorganisms that are adapted to produce a chemical product having malonyl-CoA as a substrate in the microbial production pathway of that chemical product, such as 3-hydroxypropionic acid (3-HP).